North A^ieric.vn Dittera. 61 



complete; first lontritudiniil vein hare; tlie auxiliary vein is very 

 close by it and diverges from it towards its end only; the two pos- 

 terior basal cells are very larjje. Front with some bristles in the 

 neighborhood of the crown only ; bordering of the mouth without 

 vibrissa?. Last segment of the abdomen of the female prolonged 

 into a blunt, cylindrical tube. 



O R T A L I I) x. 

 Neuration of the wings complete; auxiliary vein separated from 

 the first longitudinal vein and running to the border of the wing in 

 the usual way, under an acute angle and remaining perfectly dis- 

 tinct in its whole length; third longitudinal vein generally with 

 coarse hairs; two posterior basal cells large, and the outward one 

 frequently' prolonged in an acute angle. Front with bristles on the 

 upper part only ; no vibrissa? at the border of the mouth ; clypeus 

 commonly very much developed, and proboscis often very mucli 

 thickened. Middle tibia? alone with spurs ; no tibise with an erect 

 bristle on the exterior side before the tip. Ovipositor of the female 

 rather flattened and horny, consisting of three elongated segments, 

 forming three drawers like those of a telescope, and ending in a 

 simple point. 



T K Y P E T I D ^. 



Neuration complete ; the end of the auxiliary vein runs steeply to 

 the border of the wing and becomes obsolete ; first longitudinal vein 

 always with bristles, the thii-d frequently, the fifth sometimes ; two 

 posterior basal cells rather large, the hindmost is often prolonged to 

 a point. Front on each side with two rows of bristles, one of which 

 is more above and interiorly, the otiier below and exteriorly. Bor- 

 der of the mouth with no vibrissje. Clypeus none or rudimentary. 

 Proboscis never incrassated. Only the middle tibiic with spurs ; all 

 tibia; without erect bristle on the outer side before the tip. Ovipos- 

 itor liorny, consisting of three elongated retractile segments like the 

 tlrawers of a telescope, the last of which ends in a simple point. 



LONCH^E I D-K. 



Neuration complete; the auxiliary vein runs to the border of the 

 wing in the usual way, under an acute angle and without becoming 

 obsolete, and is verv near to the first longitudinal vein ; this vein is 

 bare; the two posterior basal cells are small. Front at each side 

 with a single row of bristles ; border of the mouth without vibrissje ; 

 clypeus rudimentary. Middle tibia? with spurs; all tibia; without 

 erect l)ristle on the exterior side before the tip. The ovipositor of 

 the female consists of three joints and is rather horny, quite flatten- 

 • ed, and ends in a simple point. 



S A P K O M Y Z I D iK. 



Neuration complete ; auxiliary vein of the usual structure, fre- 

 quently verv much approximated to the first longitudinal vein ; costa 

 of the wings without bristles or marginal spine ; longitudinal veins 

 without peculiar hairs ; posterior basal cells small. Front with a 



